There is a continuing interest in the preparation of lager beer having a more mild or bland character than conventional lager beer. One reason for the interest is that there appears to be substantial potential market for flavored beers which are prepared by adding a non-beer flavor to a bland relatively flavorless beer base.
Flavored beers have been marketed for many years in Europe. In Germany a mixture of beer and concentrated raspberry juice is preferred; in France a blend of beer and lemonade or limeade is popular; in England "shandy", a mixture of beer and lemonade or lime juice is available; and in Belgium mixtures of beer and cherry juice and beer and grenadine syrup are sold.
Another reason that there is a continuing interest in the preparation of a bland beer is that there is a substantial number of persons who presently do not drink beer because they dislike its characteristic taste. These persons are potential consumers of a bland beer.
Historically, there are two general methods of fermenting malt beverages. For the production of ale-type beers, a top-fermentation process is used which utilizes a species of yeast which tends to rise to the surface of the fermenting wort. The temperature during top-fermentation is conventionally regulated at about 15.degree.-20.degree. C. (58.degree.-68.degree. F.) throughout the most active period of fermentation. For the production of lager-type beers, a bottom-fermentation process is used which utilizes a species of yeast that remains more or less uniformly suspended throughout the fermenting wort during active fermentation by natural agitation created by ascending CO.sub.2 bubbles, then settles to a more or less compact layer on the bottom of the fermentation vessel as fermentation reaches completion. The temperature during a bottom-fermentation is conventionally regulated at about 10.degree.-15.degree. C. (50.degree.-58.degree. F.) during active fermentation.
It is known that if the temperature during a lager beer fermentation is increased, the fermentation will be accelerated. However, the beer thus obtained has an undesirable winey flavor which is not typical of a lager beer. This winey off-flavor is known to be related to increased amounts of beer volatile compounds, variously known as fusel or "higher" alcohols and esters.
In our earlier applications, Ser. No. 622,001, filed Oct. 14, 1975, now abandoned, and Ser. No. 750,509, filed Dec. 14, 1976, now U.S. Pat. No. 4,068,005 we disclosed a method of reducing the length of time required to prepare a normal tasting lager beer which method comprised conducting the fermentation at an elevated temperature while maintaining the dissolved carbon dioxide concentration in the fermenting wort at about 1.5 to about 2.0 cc of fermenting wort by use of an appropriate CO.sub.2 overpressure of about 2 to about 20 psig. The formation of the winey flavored volatiles which normally result from the use of elevated temperatures in lager fermentation is suppressed when the dissolved carbon dioxide levels are maintained within the described limits.
Our earlier applications contain an extensive discussion of prior practices relating to the fermentation of lager beer and are incorporated by reference herein.